Over the years, pinball type games have and continue to be a popular yet challenging source of amusement and entertainment. The typical pinball machine includes a playfield which is downwardly inclined toward the player. The playfield consists of a number of play components, e.g. bumpers, ramps, flippers, guide rails, slots and targets. The player, positioned behind the lower end of the playfield, controls the game by operating flippers to direct pinballs at play components in order to score points. The pinballs travel around the playfield, affected by flippers, other play components and the force of gravity, which compels the pinballs down the inclined surface to the lower end of the playfield. Certain of the scoring targets have sensors, connected to circuitry which activates scoring displays. Play continues until the pinball traveling around the playfield is caused to exit the playfield by dropping into a hole, referred to as a drain hole, usually located behind flippers at the lower end of the playfield.
Having dropped into the drain hole, the pinball falls into a pinball trough, usually secured underneath the playfield surface, out of sight of the player. A most commonly used trough, one found in the design of thousands of pinball machines currently in operation, is the subject of U.S. Pat. No. 5,358,243. As seen in this patent, the trough is formed as a U-shaped channel, mounted beneath the playfield and extending between the drain hole and the shooter's lane, i.e. the point where the pinball is propelled back onto the playfield. The bottom surface of the trough is downwardly inclined and has a V-shaped groove. This configuration allows pinballs which drop through the drain hole to roll downward, along the groove, towards the shooter's lane. When the player pushes a button or otherwise activates a switch to bring a pinball which is within the trough onto the playfield, a solenoid plunger forces the pinball which is “on deck”, that is nearest to the shooter's lane, up through an opening to the playfield.
Optical sensors mounted on the trough are positioned to detect the presence or absence of pinballs in the trough and, hence the movement of the machine's sensors which control the electronic play components on the playfield. If these sensors detect that pinballs are present in the trough and a pinball on deck which has yet to be sent for delivery to the playfield, the electronic play components will not be activated. If the sensors detect pinballs in the trough, but no pinball on deck, the system will presume there is a pinball in play (e.g. stuck on the playfield) and direct the game's electronic play components to operate. The game's electronics have a routine to begin a solenoid activation sequence (hunting), if a ball is missing and presumed still on the playfield. This will interrupt play and sometimes reset the game.
As the pinball troughs are usually made of a soft metal like tin, the constant impacting of the pinballs, which are made of a harder metal like chrome, on the troughs' bottom surfaces, causes these surfaces to become increasingly worn. Additionally, the pinballs themselves are subject to a number of abrasive forces, including the continual contact with the play components due to solenoid activation, contact with other pinballs, vibrations transmitted through the playfield surface and player agitation, and from wear caused by the pinballs being dropped onto the troughs. These forces cause abrasive surfaces on the pinballs. The pinballs, with their abrasive surfaces, resting on the bottom surfaces of the troughs, vibrate due to the agitation and movement of the pinball machines during routine play. This constant vibration results in the abrasive surfaces of the pinballs causing additional rutting and pitting and increased wear on the bottom surfaces of the troughs.
The pitting and wear which inevitably occurs on the bottom surface of the trough, in combination with the pitted pinballs, results in a pitted and uneven bottom surface. This encumbers the free movement of the pinballs as they roll down the inclined surface of the trough. In fact, the abrasively worn pinballs, once they fall from the drain hole onto the pitted trough, often have a tendency to roll to a stop within the trough, well short of the on deck location. Since, when this happens, there is no pinball in the on deck position, activation by the player who is calling for the delivery of a pinball onto the playfield will have no effect. This will usually result in the player pushing or attempting to tilt the pinball machine to move the pinball, which, at the very least disrupts the game and, at most, will damage the machine.
In addition, since the optical sensors mounted on the trough detect the presence of pinballs in the trough and no pinball on deck, the sensors and hence the system presume that there is a pinball in play and send signals to the electronic play components to continue to operate. As there is, in fact, no ball in play, the play components are needlessly being operated, causing undue wear and tear of these components.
There have been various attempts to address the problem of damaged pinball machine troughs. Most of these have centered around providing various types of shims to incline pinball machines with worn pinballs and troughs, thus further inclining troughs so that the pinballs are free to travel towards the shooter's lane. However, this has the obvious disadvantage of disrupting the calibrated operation of the machine, which is designed to operate with its components at a given degree to the horizontal. Replacement of the pinball trough is another option which has been considered; however, as the pinball machines using these troughs are no longer being manufactured, finding new pinball troughs is often an impossible task. Manufacturing a custom pinball trough is expensive and producing them in quantity would not be cost effective.